Automated sequential air sampler

ABSTRACT

An automated sequential air sampler that is highly suitable for being remotely situated to obtain a plurality of air samples at predetermined intervals of time over an extended time period, is disclosed. The air sampler includes a plurality of piston pumps that may be in the form of hypodermic syringes. Each pump operates to obtain an air sample whenever a plunger thereof is retracted to have air drawn through an inlet needle into an interior chamber thereof. The inlet to each pump is automatically sealed by having the inlnet needle thereof covered by a septum that is drawn against said inlet with a guide rod on which it is mounted and in response to the plunger reaching the end of its stroke. Sequential retraction of the several syringe plungers is accomplished by operation of a timed retractor assembly which functions to retract individual plungers at predetermined intervals of time.

United States Fatent [1 1 [111 aaaaoat Griffith May 20, 1975 AUTOMATEDSEQUENTIAL AIR SAMPLER [57] ABSTRACT [75] Inventor: George A. Griffith,Pasadena, Calif. An automated sequential air Sampler that is higmy [73]Assignee: California Institute of Technology, suitable for beingremotely situated to obtain a plural- Pasadena, Calif ity of air samplesat predetermined intervals of time over an extended time period, isdisclosed. The air [22] Flled: June 1974 sampler includes a plurality ofpiston pumps that may [21] N 4 2 140 be in the form of hypodermicsyringes. Each pump operates to obtain an air sample whenever a plungerthereof is retracted to have air drawn through an inlet [52] US. Cl73/4215 R needle into an interior chamber thereof The inlet to [51]lift. Cl. G01 l/24 each pump is automatically Sealed by having theinlnet [58] Field of Search 73/4215 R, 425.6, 28; needle thereof coveredby a septum that is drawn 23/254 R against said inlet with a guide rodon which it is mounted and in response to the plunger reaching the [56]References Clted end of its stroke. Sequential retraction of the severalUNITED STATES PATENTS syringe plungers is accomplished by operation of a2,411,157 11/1946 Fene et a1. 73/4215 R timed retractor assembly whichfunctions to retract 3,044,300 7/1962 Eden individual plungers atpredetermined intervals of time. 3,166,938 1/1965 Weyrauch.....3,334,788 8/1967 Hamilton 3,765,402 10/1973 Grabhorn l28/DIG. 5 37Claims, 11 Drawing Figures Primary Examiner-S. Clement Swisher Attorney,Agent, or FirmEric T. S. Chung PiJENTED h'AYZUISYS SHEET 10F 3 o 5 y m o4 8 u All 7 5 5 80 6 My 3 w obs 4 Z I ll... 6 j d 1 d 4 Z 2 m u e. 2 7.5 m m 6 5 wk b i PATENTED HAY 2 01975 sum 2 or 3 l 55!!!! ll i AUTOMATEDSEQUENTIAL AIR SAMPLER BACKGROUND OF THE INVENTION 1. Field of theInvention This invention generally relates to air sampling devices. Morespecifically, the present invention concerns an automated sequential airsampler that is particularly suitable for remotely obtaining a pluralityof air samples at spaced predetermined intervals of time.

2. Description of the Prior Art Atmospheric studies such as may beattendant to air pollutant monitoring requires that ambient air samplesbe obtained for analysis. Typically, such samples may be obtainedmanually and returned to a laboratory for analysis. Obtaining samples atdifferent time intervals in the course of a day or other time period maytypically involve a person being required to make several trips to andfrom the site at which the air samples are to be taken, i.e., thevicinity of a factory, a downtown area, a mountain top, etc. In thealternative, the person taking the air sample may choose to remain atthe site at which samples are being taken for the entire time periodduring which samples are desired. Economic considerations, such as thecost of manpower, obviously make highly desirable the availability of anautomated sequential air sampler that can be readily implaced and laterretrieved after several air samples have been automatically obtained.

There are currently available sequentially operated instruments that aredesigned to collect particulate matter in the air. Also available areinstruments that operate to continuously collect certain gaseouscompounds by absorption in a liquid solution. Most of such units areeither not portable or difficult to transport. Such prior art devicesare also fairly expensive.

Numerous air sampling devices designed for manual operation have beenheretofore used. As an example, evacuated stainless steel containers,plastic bags, and plastic squeeze bottles have been used. Piston pumpsin the form of hypodermic syringes have also been employed. However,such prior art devices have in the past been primarily employed assingle units and have not been used in combination to provide anautomated sequential air sampler capable of obtaining several airsamples at predetermined time intervals and without the requirement thatan operator or other attendant be present.

One of the prime difficulties that has thwarted successful design of aportable sequential air sampler is the need for an effective means forsealing the container in which the air'sample is contained once it isobtained. An acceptable solution must be effective, simple, easy tomanufacture, and capable of being reliably activated after each sampleis obtained.

Accordingly, it is the intention of the subject invention to provide anautomated sequential air sampler that is simple, capable of beingeconomically manufactured, and effective to obtain plural air samples atpredetermined time intervals without requiring the contin uous presenceof an operator or other attendant.

SUMMARY OF THE INVENTION Briefly described, the present inventioninvolves an air sampling device that is capable of being remotelysituated for the purpose of obtaining air samples at predetermined timeintervals over a selected period of time without the need for manualoperation of individual sampling units forming a part thereof.

More particularly, the subject automated air sampler includes aplurality of piston pumps each adapted to have the plunger thereofretracted at scheduled time intervals to have air samples drawn into theinterior cavity of each said pump. The input through which air is drawninto said cavity is automatically sealed by automatic placement of aseptum over said inlet in response to a guide rod on which said septumis mounted interacting with said plunger at the end of its stroke.Retraction of the individual plungers is accomplished with a retractorassembly that is attached to each of said plungers and which is designedto retract individual plungers only at scheduled time intervals.

The objects and many attendant advantages of the invention will be morereadily appreciated as the same becomes better understood by referenceto the following detailed description which is to be considered inconnection with the accompanying drawings wherein like reference symbolsdesignate like parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagramillustrating a perspective view of a first embodiment of an automatedsequential air sampler in accordance with the present invention.

FIG. 2 is a schematic diagram illustrating an end view of the airsampler device shown in FIG. 1.

FIG. 3 is a schematic diagram illustrating a piston pump that is useablefor forming individual air sampling units in accordance with the presentinvention.

FIG. 4 is a schematic diagram illustrating an end view of the pistonpump shown in FIG. 3.

FIG. 5 is a schematic diagram illustrating a perspective view of asecond embodiment of an automated air sampler in accordance with thepresent invention.

FIG. 6 is a top view of an alternative timed retractor assembly that isuseable with an automated air sampler in accordance with the presentinvention.

FIGS. 7 and 8 are schematic diagrams illustrating crosssectional viewsof the retractor assembly shown in FIG. 6.

FIG. 9 is a schematic diagram illustrating a partial top view of theretractor assembly illustrated by FIG. 6 after a first section thereofhas nearly completed a rotation to be in position to activate a secondsection thereof.

FIG. 10 is a schematic diagram illustrating a crosssectional view of theretractor assembly shown in FIG. 9.

FIG. 11 is a schematic diagram illustrating a further view of theretractor assembly shown in FIG. 9 after a second section thereof hascommenced operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to thedrawings, FIGS. 1 through 4 illustrates a first embodiment of anautomated sequential air sampler in accordance with the presentinvention. As shown, an air sampler includes a plurality of piston pumps2, 4, 6, and 8 which are removably mounted on a supporting channel plate10. Each piston pump 2, 4, 6 and 8 essentially includes an inlet needle12, a cylindrical housing 14, and a piston-like plunger 16 whichfunctions to draw air through the inlet needle 12 into the interiorcavity 18 of the housing 14 when the plunger 16 into the interior cavity18 of the housing 14 will evacuate said cavity 18 by forcing air thereinto be ejected through the inlet needle 12. The plunger 16 may besuitably equipped to have a disk seal 20 at the interior tip thereofwhich seal 20 is preferably sized to snugly fit within, and abut, theinterior walls of the cylindrical housing 14 to thereby form an airtightseal in a manner well known in the prior art. A somewhat resilientmaterial such as rubber may be used as the seal 20.

Sealing of the individual piston pumps 2, 4, 6 and 8 after an air samplehas been drawn into the interior cavity 18 thereof, is required tomaintain the sample until such time as it can be transported to alaboratory or like facility for analysis. Sealing of individual pistonpumps is accomplished with a septum 22 that may be mounted at one end ofa guide rod 24. As shown, the guide rod 24 is slidably maintained on thepiston pump to which it corresponds by a guide ring 26 and a positioningarm 28.

The guide ring 26 should be appropriately sized to have the interiordiameter thereof be slightly larger than the exterior diameter of thehousing 14 to permit the guide ring 26 and the guide rod 24 to be easilymoved or slid along the axis of the housing 14.

Similarly, the positioning arm 28 may be provided with an aperture 30through which the input needle 12 is extended. The size or diameter ofthe aperture 30 should be sufficiently large to accommodate the outerdiameter of the needle 12 and thereby permit sliding of the positioningarm 28 along the length of the needle 12.

The opposite end of the guide rod 24 is provided with an enlarged stopdisc 32. The stop disc 32 is situated to engage a pair of upstandingarms formed on a U-plate 34 which is attached to the exterior end 36 ofthe plunger 16. As shown, the guide rod 24 extends between saidupstanding arms such that upon near full retraction of the plunger 16,the upstanding arms of the U-pla'te 34 will contact the stop disc 32 andmove or pull the guide rod 24 laterally rearward with respect to thepiston pump as the plunger 16 continues to full retraction. Upon suchfull retraction of the plunger 16, the septum 22 will abut the tip 38 ofthe input needle 12. The tip 38 is preferably squared to promote an airtight seal when covered by the septum 22.

Clearly, the guide rod should have a length that would permit the septum22 to abut the tip 38 of the input needle 12 when the plunger 16 isfully retracted in accordance with the invention. To this end, fineadjustments of the distance between the face of the septum 22 and thestop disc 32 may be provided for by having either, or both, the septum22 and the stop disc 32 movably mounted on the guide rod 24 to allowforward or rearward adjustments. For example, the stop disc 32 may bethreaded on the end of the guide rod 24 to allow turning and therebypermit adjustment of its distance from the septum 22. Similarly, theseptum 22 may be attached to the end of the guide rod 24 with a mountthat is threaded therethrough to allow forward and rearward adjustment.

The septum 22 may be made of any resilient material such as rubber orthe like. The entire septum 22 need not be made of resilient material;however, the fact thereof contacting the needle 12 should be made ofsuch resilient material. In such case, for example, a disc of rubbermaterial may be appropriately maintained in a cup-like recepticle whichis in turn mounted on the forward end of the guide rod 24.

Referring to FIG. 1, each of the piston pumps 2, 4, 6 and 8 are mountedon the channel plate 10 by being extended through an appropriately sizedhole in a front wall 40 thereof. The rearward end of the housing 14 ofeach pump is provided with a flange 12, or the like, which is somewhatlarger than the holes provided in the forward wall 40 of the channelplate 10. Any appropriate means, such as a thumb screw and mounting wirecombination 44, may be used to removably secure the individual pumps tothe forward wall 40. The plunger 16 of each of the pumps 2, 4, 6 and 8hence would be drawn across the channel plate 10 as it is retracted.

The U-plates 34 are attached to be removably clipped onto the exteriorend 36 of the respective plungers 16 so as not to impede or hinder themounting and/or removal of piston pumps on the forward wall 40 of thechannel plate 10. Accordingly, assembling the subject sequential airsampler in preparation for the obtaining of air samples would initiallysimply involve fastening each of the piston pumps to the channel plateby manipulation of the thumb screw assembly 44, positioning a guide rod24 on each pump, and attaching a U-plate 34 to the exterior end 36 ofthe piston 16 to each pump. Conversely, removal of the pumps for airanalysis would simply require manipulation of the thumb screw assembly44 and removal of the U-plate 34 to allow the individual pumps to beremoved.

Although four piston pumps have been illustrated, it is to be understoodthat a greater or lessor number of pumps may be employed.

Operation of the individual piston pumps at predetermined time intervalsmay be accomplished by the use of a timed retractor assembly that wouldbe necessarily connected to the individual plungers 16 of the respectivepumps to produce retraction thereof. FIGS. 1 through 4 illustrate afirst embodiment of a suitable timed retractor assembly that would beuseable in accordance with the subject invention. FIG. 5 illustrates asecond embodiment of a retractor assembly while FIGS. 6 through 11illustrate a third embodiment of a retractor assembly that would besuitable.

Referring to FIGS. 1 through 4, a said first embodiment of a suitabletimed retractor assembly includes a rotary mechanical timer 46 thatrotates an armature 47 on which a plurality of trigger arms 48 aremounted to contact and move corresponding L-shaped lever arms 50.Forward movement of said L-shaped lever arms 50 cause release of theretention pins 52 respectively associated therewith. Coil springs 54 areused to provide a spring tension on each of the individual plungers 16.As shown, a coil spring 54 is attached between the exterior end 36 ofeach plunger 16, through the U-plate 34 as is necessary, and therearward wall 56 of the channel plate 10.

When the individual plungers 16 are fully inserted into the interiorchambers 18 of the housing 14 of the respective pumps, the associatedspring 54 attached thereto is expanded or stretched as shown in FIG. 2and in FIG. 1 with respect to the pumps 2, 4, and 6. The individualplungers 16 are retained in such an inserted position by having the tip58 of a corresponding pin 52 inserted through an aperture 60 on theLshaped lever arm 50 as shown by FIGS. 2 and 4. The opposite end 60 ofthe retention pin 52 may be suitably anchored or fastened to a face ofthe forward wall 40 of the channel plate by being looped through ananchor provided on the wall 40 for this purpose. As shown in FIG. 2,continued rotation of a trigger arm 48 first results in contact with asassociated L-shaped lever arm 50 and finally forward movement of suchlever arm 50, as shown by the phantom lines 48' and 50 of FIG. 2. Suchforward movement of the L-shaped lever arm 50 causes a pivoting movementwith respect to a retainer 62 and thereby permits the tip 58 of theretention pin 52 to be extracted from the aperture 60 and thereby becomedisengaged from its associated L-shaped lever arm 50. The resultingcontraction of the associated spring 54 causes retraction of the plunger16 as is shown by FIG. 3. An air sample is thereby drawn into theinterior cavity 18 of the housing 14 through the input needle 12. Asearlier explained, the septum 22 is pulled rearwardly by lateralmovement of the guide rod 24 in response to interaction of the stop disc32 and the U- plate 32 as the plunger 16 reaches full retraction.

The time at which the individual L-shaped lever arm 50 are contacted bycorresponding trigger arms 48 may be readily predetermined and adjustedfor by rearrangement of the relative radial positioning of the triggerarms 48 with respect to each other about the armature 47. Referring toFIG. 1, let it be assumed that the rotary mechanical timer causes thearmature 47 to be rotated in the direction of the arrow 66. The triggerarm 48A would then contact its corresponding L- shaped lever arm 50before trigger arm 48B reaches its corresponding L-shaped lever arm 50.As shown, if the displacement between the trigger arms 48A and 48B isapproximately 90 and the mechanical timer 46 is designed to rotate thearmature 47 at a rate of one revolution per hour, all pumps would beactuated within one hour and the piston pumps 2 and 4 would besuccessively actuated in an interval of minutes. Clearly, by employingrotary mechanical timers or any other movers that are designed to rotatethe armature 47 at a different rate, the time period over which allpiston pumps would be actuated can be made longer or shorter as isdesired. Correspondingly, the time intervals between the actuation ofsuccessive piston pumps can be varied.

Referring now to FIG. 5, an alternative timed retractor assembly mayinclude the use of a plurality of chains 66A through 66D, such as ladderchains, each having a different length. One end of each of the chains66A through 66D is connected to the end 36 of the piston 16 to beretracted thereby via its U-plate 34 as may be necessary. As shown, theother end of each chain 66A through 66D is situated to be engaged by acorresponding one of the drive sprockets 68A through 68D which have theconventional plurality of radially extending teeth. The sprocket wheels68A through 68D are mounted on an armature 70 which is connected to berotated, i.e., in the direction indicated by an arrow 72, by anappropriate motor 74 of conventional design.

The armature 70 may be supported at its ends by being In operation, asthe armature and hence the respective sprocket wheels 68A through 68Dare rotated by operation of the motor 74, each of the chains 66A through66D are drawn over associated sprocketswith which each is engaged. Thespecific times at which the individual piston pumps are actuated byhaving the plungers 61 thereof retracted, is determined by the length ofthe chain attached thereto. The longer the length of a chain, the moredelayed will be the actuation of the pump attached thereto due to therequirement that extra or slack portions of the chain must first bedrawn across a sprocket before a plunger to which the chain is attachedwill commence to be retracted. Clearly, to have successive actuation ofpumps, the chains 68A through 68D would be successively longer. Theactual length of chain that must be used to provide any desired time ofactuation would be calibrated for, or tailored to, a specific rate ofrotation of the armature 70 and/or the motor 74. Any conventional motormay be used. Preferably, a motor that can be adapted to be operated witha portable power pack, i.e., battery, electrical, etc. would beadvantageous for operation at remote sites.

In the embodiment of FIG. 5 the rate at which a plunger 16 is retractedmay also be varied by simply altering the diameter of the sprocketwheels 68A through 68D. The rate of retraction would be increased as thediameter of a sprocket is decreased. It is noted that in the embodimentillustrated by FIGS. 1 through 4, the plungers 16 are quickly retractedto effectively obtain what may be considered in a practical sense as aninstantaneous air sample. By comparison, slow withdrawal of the plungers16, as may be accomplished by the embodiment of FIG. 5, would permit thecollection of an air sample over a somewhat extended time period toprovide what is sometimes referred to as an integrated air sample.

Each of the chains 66A through 66D are provided with an extended channelsuch that upon thev plunger 16 to which the chain is attached beingfully retracted, such channel 80 eliminates engagement of a chain withthe teeth of its associated sprocket and permits the chain to simplyslip with respect to the sprocket wheel so as to prevent completewithdrawal of the plunger 16 from its cylindrical housing 14. Clearly,the rate at which the chains 66A through 66D are drawn by the respectivesprockets 68A through 68D depends on the rate of rotation thereof andcan be as fast or as slow as is desired. It is to be understood that therespective chains may be attached in any convenient manner to theplungers 16 and/or the U-plates 34 such as by simply having a hook andeye arrangement (not illustrated).

A further embodiment of a timed retractor assembly suitable for use withthe subject invention is illustrated by FIGS. 6 through 11. Theindividual chains 66A 1 through 66D have been omitted for the purpose ofbrevity and simplification of the drawings. Referring to FIG. 6, it maybe observed that the drive motor 74 is positioned to have the armature70, or an extension thereof, extended through the support panel 75. Thearmature is shortened in this embodiment and is attached to the closestsprocket 68A. The next positioned sprockets68B and 68C are freelyrotatable about an axle 82. Similarly, drive spacers or spools 84 and 86which are situated between successive sprock-v ets, i.e., drive spacer84 is positioned between sprockets 68A and 68B while drive spacer 86 issituated between sprockets 68B and 68C, are mounted to be freelyrotatable about the axle 82.

As shownby FIG. 6, he sprockets 68A, 68B and 68C are equipped with pinswhich laterally extend out of the side walls of the respectivesprockets. For example, the sprocket 68A is provided with a pin 88,sprocket 68B is provided with pins 90 and 92, and sprocket 68C isprovided with pins 94 and 96. Additional sprockets would be similarlyconstructed. Spacers 84 and 86 are provided with pins which extendradially from enlarged portions at either end thereof. Specifically,spacer 84 is provided with pins 98 and 100 while spacer 86 is providedwith pins 102 and 104. The next successive spacer 87 between spacer 68Cand 681) (not shown) would have a similar pair of pins including the pin106.

Assuming that the respective pins 88, 90, 92, 94, 96, 98, 100, 102, I04and 106 are initially situated as shown in FIG. 6, rotation of thearmature 70 in the direction indicated by the arrow 108 will causerotation of the first sprocket 68A connected thereto without anyrotational effect on the remaining spacers and sprockets freelysupported on the axle 82. FIGS. 7 and 8 illustrate side cross-sectionalviews of the sprocket 68A and the spacer 84, respectively, in theirinitial positions as shown by FIG. 6. As a near complete rotation of thesprocket 68A is completed, the pin 88 will be positioned behind the pin98, as shown by FIGS. 9 and 10, such that continued rotation of thesprocket 68A will produce rotation of the spacer 84 and also thesprocket 68B by reason of the interaction of pins 90 and 100, as shownby FIG. 11. Rotation of the sprockets 68A and 68B and the interveningspacer 84 will leave the next successive spacer 86 unaffected. Upon nearcompletion of a rotation of the sprocket 68B, the pin 92 will becomepositioned behind the pin 102 of the spacer 86. Continued rotation ofthe sprocket 683 will produce rotation of the spacer 87 and a sprocketassociated therewith in unison with the already rotating sprockets 68Aand 68B and spacers 84 and 86.

It is clear that by altering the initial positions of the pins on thesprockets with respect to the pins on the spacers, the time at which thenext successive adjacent sprocket would be driven can be prescheduled.For example, were the pin 88 repositioned to be 180away from itsposition shown in FIGS. 7 and 7, i.e., as shown by the dotted circle 110in FIG. 7, the interval between the start of sprocket 68A and the startof sprocket 68B would be cut in half assuming that the pins 90 and 100are initially positioned as shown in FIGS. 6 and 8. Similarly, as afurther example, if the pins 88 and 98 are initially positioned as shownin FIGS. 6 and 7, but the positions of the pins 90 and 100 are reversedto have the pin 100 be in front of rather than in back of the pin 90,the spacer 84 would complete on full rotation before the pin 100 wouldbe positioned behind the pin 90 and thereby commence driving thesprocket 68B by continued rotation. The interval of time between thestart of sprocket 68A and the start of sprocket 683 would thereby beeffectively near doubled in that sprocket 68A would be required to makea complete rotation before causing rotation of the spacer 84 which inturn would be required to complete a near full rotation befoe engagingthe sprocket 68B.

The sprockets 68A, 68B, etc. may readily be provided with a circulargrouping of holes along the periphery, and in the sides, thereof toaccommodate movement of the pins 88, 90, 92, etc. to different positionsthereon and thereby permit adjustment, in smaller increments, of thetime intervals between rotation of successive sprockets. Similarly, thespacers 84, 86, etc. may be provided with a series of holes toaccommodate movement of the pins 98, 100, 102 etc. thereon to also allowfiner time adjustments.

Although operation of the embodiment of FIGS. 6 through 11 has beendescribed without reference to drive chains, it is clear that chainssimilar to the chains 66A through 66D would be used to retract thatrespective plunger 16 by being connected thereto.

It is further clear that in addition to using the drive mechanism ofFIGS. 6 through 11 to alter the time intervals between the start ofsuccessive sprockets and hence the retracting of corresponding pistons16, the length of the chains 66A through 66D may also be varied as wasdescribed in conjunction with FIG. 5, to further increase or decreasethe intervals of time between actuation of successive pistons. Further,the diameter of the individual sprockets 68A, 68B, 68C etc. can beincreased or decreased to thereby alter the speed at which theindividual pistons are retracted as was earlier explained.

It is to be understood that although a single motor for operating aplurality of piston pumps has been discussed in the foregoingdescription, the subject invention may be constructed to have separatemotors for each of the piston pumps wherein the individual motors aretimely energized to have pumps operated in accordance with a desiredtime schedule.

From the foregoing it is now clear that the subject invention providesan automated sequential air sampler that is simple in construction andreadily portable, and which would be highly effective in obtaining airsamples without the need for manual operation of the individual airsampling units or for continuous attention of an attendant.

While a preferred embodiment of the present invention has been describedhereinabove, it is intended that all matter contained in the abovedescription and shown in the accompanying drawings be interpreted asillustrative and not in a limiting sense and that all modifications,constructions and arrangements which fall within the scope and spirit ofthe invention may be made.

What is claimed is:

1. An air sampling device for obtaining a plurality of air samples atscheduled time intervals, said air sampling device comprising:

a plurality of piston pumps each having a housing forming an interiorchamber, an inlet port member communicating with said chamber, and aplunger which is partially retracted from within said cham ber of saidhousing to draw air into said chamber through said inlet port memberwhen a said piston pump is actuated;

a plurality of sealer means respectively connected to a different one ofsaid pumps for sealing off said inlet port member thereof in response tothe plunger thereof being partially retracted from within the chamberthereof by a predetermined distance; and

actuator means for actuating each of said plurality of pumps atscheduled time intervals.

2. The device defined by claim 1, said piston pumps being elongate andfurther including a stopper arm attached to said plunger, said sealermeans including:

an elongated member positioned to extend along the length of a pumpassociated therewith; and

cover means attached at an end of said elongate member for preventingthe passage of air through an inlet port member when positioned to coversaid inlet port by being drawn thereagainst in response to being engagedby said stopper arm when said plunger is retracted by said predetermineddistance.

3. The device defined by claim 2, said elongate member further includinga nub attached on said elongate member to be engaged by said stopperarm, said stopper arm having a central groove for receiving saidelongate member therein, said stopper arm engaging said nub on saidelongate member to draw said cover means against said inlet port.

4. The device defined by claim 3, said cover means and said nub beingmovably on said elongate member to allow adjustment of the distancetherebetween.

5. The device defined by claim 4, wherein the distance between saidcover means and said nub is equal to the distance between the tip ofsaid inlet port member and the outermost end of a plunger when retractedby said predetermined distance.

6. The device defined by claim 2, said sealer means further including:

a positioning arm attached to and extending from said elongate member,said positioning arm having an aperture for receiving said inlet portmember which is extended therethrough; and

a guide member attached to said elongate member for slideably movingwith respect to said housing of an associated pump for guiding saidelongate member when moved with respect to said housing.

7. The device defined by claim 1, said air sampler device furtherincluding a mount on which said plurality of piston pumps are removablymounted, said mount configured to have first and second walls connectedto a base panel to form a channel therebetween, said plurality of pistonpumps being attached to said first wall.

8. The device defined by claim 7, said actuator means including:

a plurality of retention means respectively associated with each of saidpumps for maintaining said plunger thereof within said interior chamberof the housing thereof;

a plurality of retracting means respectively connected to a plunger ofone of said pumps for retracting a plunger connected thereto by saidpredetermined distance in response to an associated retention meansbeing released; and

trigger means for releasing each of said retention means at scheduledtime intervals.

9. The device defined by claim 8, said retracting means including aspring which is attached between the outermost end of a plunger to beretracted and said second wall of said channel mount.

10. The device defined by claim 8, said retention means including alatching pin and a latching arm having means for receiving said latchingpin and thereby maintaining said latching pin in a position preventingretraction of a plunger retained thereby, said latching arm beingmounted to be pivoted by said trigger means, whereby said latching pinis released by said latching arm when pivoted by said trigger means toallow retrac tion of said plunger.

11. The device defined by claim 10, said trigger means including: 5 anarmature;

a plurality of trigger arms mounted on said armature;

and

means for rotating said armature about the longitudinal axis thereofwhereby said trigger arms are moved to contact and thereby causepivoting of said latching arms to produce release of correspondinglatching pins and consequent retraction of plungers retained thereby.

12. The device defined by claim 1 1, wherein the trigger arms aremounted on said armature at radial angles with respect to thelongitudinal axis thereof that are determinative of the time interval atwhich individual ones of said plurality of pumps are actuated.

13. The device defined by claim 1, said actuator means including:

a plurality of retracting means respectively connected to'a plunger of adifferent one of said plurality of pumps for retracting the plungerconnected thereto at predetermined times; and

timing means for initiating the retraction of the respective plungers ofsaid plurality of pumps in accordance with a predetermined timeschedule.

14. The device defined by claim 13, said plurality of retracting meanseach including a chain and having a predetermined different length, afirst end portion of each chain connected to the outermost end of adifferent one of said plungers, a second end portion of each chainconnected to said timing means, said chains being drawn away from saidplungers by said timing means.

15. The device defined in claim 14, the lengths of said chainsdetermining the succession in which the plungers connected thereto areretracted, the plunger connected to the shortest chain being retractedfirst and the plunger attached to the longest chain being retractedlast.

16. The device defined by claim 13, said timing means including:

a plurality of sprockets each positioned to be engageable with adifferent one of said retracting means; and

mover means for driving said sprockets to have said retracting meansengaged therewith retract plungers connected thereto at saidpredetermined times.

17. The device defined by claim 16, said mover means including anarmature that is adapted to be rotated about the longitudinal axisthereof, said armature being connected to at least one of said sprocketsto cause rotation thereof.

18. The device defined by claim 14, said timing means including:

a plurality of sprockets each positioned to engage a different one ofsaid chains; and

mover means for causing said sprockets to be rotated.

to have chains engaged therewith drawn in a direction away from theplungers connected thereto to produce retraction of said plungersconnected thereto.

19. The device defined by claim 18, said sprockets each having adiameter corresponding to a desired rate at which an associated plungeris to be retracted.

20. The device defined by claim 19, wherein said mover means isconnected to rotate said sprockets in unison.

21. The device defined by claim '19, wherein said mover means isconnected to rotate said sprockets successively.

22. The device defined by claim 5, said air sampler device furtherincluding a mount on which said plurality of piston pumps are removablymounted, said mount configured to have first and second walls connectedto a base panel to form a channel therebetween, said plurality of pistonpumps being attached to said first wall.

23. The device defined by claim 22, said actuator means including:

a plurality of retention means respectively associated with each of saidpumps for maintaining said plunger thereof within said interior chamberof the housing thereof;

a plurality of retracting means respectively connected to a plunger ofone of said pumps for retracting a plunger connected thereto by saidpredetermined distance in response to an associated retention meansbeing released; and

trigger means for releasing each of said retention means at scheduledtime intervals.

24. The device defined by claim 23, said retracting means including aspring which is attached between the outermost end of a plunger to beretracted and said second wall of said channel mount.

25. The device defined by claim 14, said retention means including alatching pin and a latching arm having means for receiving said latchingpin and thereby maintaining said latching pin in a position preventingretraction of a plunger retained thereby, said latching arm beingmounted to be pivoted by said trigger means, whereby said latching pinis released by said latching arm when pivoted by said trigger means toallow retraction of said plunger.

26. The device defined by claim 25, said trigger means including:

an armature;

a plurality of trigger arms mounted on said armature;

and

means for rotating said armature about the longitudinal axis thereofwhereby said trigger arms are moved to contact and thereby causepivoting of said latching arms to produce release of correspondinglatching pins and consequent retraction of plungers retained thereby.

27. The device defined by claim 26, wherein the trigger arms are mountedon said armature at radial angles with respect to the longitudinal axisthereof that are determinative of the time intervals at which individualones of said plurality of pumps are actuated.

28. The device defined by claim 5, said actuator means including:

a plurality of retracting means respectively connected to a plunger of adifferent one of said plurality of pumps for retracting the plungerconnected thereto at predetermined times; and

timing means for initiating the retraction of the respective plungers ofsaid plurality of pumps in accordance with a predetermined timeschedule.

29. The device defined by claim 28, said plurality of retracting meanseach including a chain and having a predetermined different length, afirst end portion of each chain connected to the outermost end of adifferent one of said plungers, a second end portion of each chainconnected to said timing means, said chains being drawn away from saidplungers by said timing means.

30. The device defined by claim 29, the lengths of said chainsdetermining the succession in which the plungers connected thereto areretracted, the plunger connected to the shorter chain being retractedfirst and the plunger attached to the longest chain being retractedlast.

31. The device defined by claim 29, said timing means including:

a plurality of sprockets each positioned to be engageable with adifferent one of said retracting means; and

mover means for driving said sprockets to have said retracting meansengaged therewith retract plungers connected thereto at saidpredetermined times.

32. The device defined by claim 29, said sprockets each having adiameter corresponding to a desired rate at which as associated plungeris to be retracted.

33. The device defined by claim 32, wherein said mover means isconnected to rotate said sprockets in unison.

34. The device defined by claim 32, wherein said mover means isconnected to rotate said sprockets successively.

35. The device defined by claim 33, said mover means including anarmature that is adapted to be rotated about the longitudinal axisthereof, said armature being connected to at least one of said sprocketsto cause rotation thereof.

36. An air sampling device for successively obtaining a plurality of airsamples, said device comprising:

a plurality of air sampler units each including a cylindrical housingdefining an interior cavity, an inlet needle connected to said cavity,and a piston-like plunger housed in said cavity for drawing an airsample through said inlet needle into said cavity as said plunger ispartially withdrawn from said cavity;

a plurality of stopper means respectively connected with a different oneof said sampler units for covering the inlet needle thereof in responseto the plunger thereof being withdrawn from the cavity thereof by apredetermined distance, said stopper means serving to prevent the escapeof an air sample through the inlet needle covered thereby;

retractor means connected to the plungers of said sampler units forpartially withdrawing each plunger for said predetermined distance inaccordance with. a selected time schedule.

37. An air sampling device for automatically obtaining an air sample,said device comprising:

an air sampler unit including a housing defining an interior cavity, aninlet needle connected to said cavity, and a piston-like plunger housedin said cavity for drawing an air sample through said inlet needle intosaid cavity as said plunger is partially withdrawn from said cavity;

stopper means connected with said sampler unit for covering said inletneedle in response to the plunger thereof being withdrawn from saidcavity by a predetermined distance, said stopper means serving toprevent the escape of an air sample through said inlet needle coveredthereby;

retractor means connected to said plunger for partially withdrawing saidplunger for said predetermined distance.

1. An air saMpling device for obtaining a plurality of air samples atscheduled time intervals, said air sampling device comprising: aplurality of piston pumps each having a housing forming an interiorchamber, an inlet port member communicating with said chamber, and aplunger which is partially retracted from within said chamber of saidhousing to draw air into said chamber through said inlet port memberwhen a said piston pump is actuated; a plurality of sealer meansrespectively connected to a different one of said pumps for sealing offsaid inlet port member thereof in response to the plunger thereof beingpartially retracted from within the chamber thereof by a predetermineddistance; and actuator means for actuating each of said plurality ofpumps at scheduled time intervals.
 2. The device defined by claim 1,said piston pumps being elongate and further including a stopper armattached to said plunger, said sealer means including: an elongatedmember positioned to extend along the length of a pump associatedtherewith; and cover means attached at an end of said elongate memberfor preventing the passage of air through an inlet port member whenpositioned to cover said inlet port by being drawn thereagainst inresponse to being engaged by said stopper arm when said plunger isretracted by said predetermined distance.
 3. The device defined by claim2, said elongate member further including a nub attached on saidelongate member to be engaged by said stopper arm, said stopper armhaving a central groove for receiving said elongate member therein, saidstopper arm engaging said nub on said elongate member to draw said covermeans against said inlet port.
 4. The device defined by claim 3, saidcover means and said nub being movably on said elongate member to allowadjustment of the distance therebetween.
 5. The device defined by claim4, wherein the distance between said cover means and said nub is equalto the distance between the tip of said inlet port member and theoutermost end of a plunger when retracted by said predetermineddistance.
 6. The device defined by claim 2, said sealer means furtherincluding: a positioning arm attached to and extending from saidelongate member, said positioning arm having an aperture for receivingsaid inlet port member which is extended therethrough; and a guidemember attached to said elongate member for slideably moving withrespect to said housing of an associated pump for guiding said elongatemember when moved with respect to said housing.
 7. The device defined byclaim 1, said air sampler device further including a mount on which saidplurality of piston pumps are removably mounted, said mount configuredto have first and second walls connected to a base panel to form achannel therebetween, said plurality of piston pumps being attached tosaid first wall.
 8. The device defined by claim 7, said actuator meansincluding: a plurality of retention means respectively associated witheach of said pumps for maintaining said plunger thereof within saidinterior chamber of the housing thereof; a plurality of retracting meansrespectively connected to a plunger of one of said pumps for retractinga plunger connected thereto by said predetermined distance in responseto an associated retention means being released; and trigger means forreleasing each of said retention means at scheduled time intervals. 9.The device defined by claim 8, said retracting means including a springwhich is attached between the outermost end of a plunger to be retractedand said second wall of said channel mount.
 10. The device defined byclaim 8, said retention means including a latching pin and a latchingarm having means for receiving said latching pin and thereby maintainingsaid latching pin in a position preventing retraction of a plungerretained thereby, said latching arm being mounted to be pivoted by saidtrigger means, whereby said latching pin is released by said latchingarm when pivOted by said trigger means to allow retraction of saidplunger.
 11. The device defined by claim 10, said trigger meansincluding: an armature; a plurality of trigger arms mounted on saidarmature; and means for rotating said armature about the longitudinalaxis thereof whereby said trigger arms are moved to contact and therebycause pivoting of said latching arms to produce release of correspondinglatching pins and consequent retraction of plungers retained thereby.12. The device defined by claim 11, wherein the trigger arms are mountedon said armature at radial angles with respect to the longitudinal axisthereof that are determinative of the time interval at which individualones of said plurality of pumps are actuated.
 13. The device defined byclaim 1, said actuator means including: a plurality of retracting meansrespectively connected to a plunger of a different one of said pluralityof pumps for retracting the plunger connected thereto at predeterminedtimes; and timing means for initiating the retraction of the respectiveplungers of said plurality of pumps in accordance with a predeterminedtime schedule.
 14. The device defined by claim 13, said plurality ofretracting means each including a chain and having a predetermineddifferent length, a first end portion of each chain connected to theoutermost end of a different one of said plungers, a second end portionof each chain connected to said timing means, said chains being drawnaway from said plungers by said timing means.
 15. The device defined inclaim 14, the lengths of said chains determining the succession in whichthe plungers connected thereto are retracted, the plunger connected tothe shortest chain being retracted first and the plunger attached to thelongest chain being retracted last.
 16. The device defined by claim 13,said timing means including: a plurality of sprockets each positioned tobe engageable with a different one of said retracting means; and movermeans for driving said sprockets to have said retracting means engagedtherewith retract plungers connected thereto at said predeterminedtimes.
 17. The device defined by claim 16, said mover means including anarmature that is adapted to be rotated about the longitudinal axisthereof, said armature being connected to at least one of said sprocketsto cause rotation thereof.
 18. The device defined by claim 14, saidtiming means including: a plurality of sprockets each positioned toengage a different one of said chains; and mover means for causing saidsprockets to be rotated to have chains engaged therewith drawn in adirection away from the plungers connected thereto to produce retractionof said plungers connected thereto.
 19. The device defined by claim 18,said sprockets each having a diameter corresponding to a desired rate atwhich an associated plunger is to be retracted.
 20. The device definedby claim 19, wherein said mover means is connected to rotate saidsprockets in unison.
 21. The device defined by claim 19, wherein saidmover means is connected to rotate said sprockets successively.
 22. Thedevice defined by claim 5, said air sampler device further including amount on which said plurality of piston pumps are removably mounted,said mount configured to have first and second walls connected to a basepanel to form a channel therebetween, said plurality of piston pumpsbeing attached to said first wall.
 23. The device defined by claim 22,said actuator means including: a plurality of retention meansrespectively associated with each of said pumps for maintaining saidplunger thereof within said interior chamber of the housing thereof; aplurality of retracting means respectively connected to a plunger of oneof said pumps for retracting a plunger connected thereto by saidpredetermined distance in response to an associated retention meansbeing released; and trigger means for releasing each of said retentionmeans at scheduLed time intervals.
 24. The device defined by claim 23,said retracting means including a spring which is attached between theoutermost end of a plunger to be retracted and said second wall of saidchannel mount.
 25. The device defined by claim 14, said retention meansincluding a latching pin and a latching arm having means for receivingsaid latching pin and thereby maintaining said latching pin in aposition preventing retraction of a plunger retained thereby, saidlatching arm being mounted to be pivoted by said trigger means, wherebysaid latching pin is released by said latching arm when pivoted by saidtrigger means to allow retraction of said plunger.
 26. The devicedefined by claim 25, said trigger means including: an armature; aplurality of trigger arms mounted on said armature; and means forrotating said armature about the longitudinal axis thereof whereby saidtrigger arms are moved to contact and thereby cause pivoting of saidlatching arms to produce release of corresponding latching pins andconsequent retraction of plungers retained thereby.
 27. The devicedefined by claim 26, wherein the trigger arms are mounted on saidarmature at radial angles with respect to the longitudinal axis thereofthat are determinative of the time intervals at which individual ones ofsaid plurality of pumps are actuated.
 28. The device defined by claim 5,said actuator means including: a plurality of retracting meansrespectively connected to a plunger of a different one of said pluralityof pumps for retracting the plunger connected thereto at predeterminedtimes; and timing means for initiating the retraction of the respectiveplungers of said plurality of pumps in accordance with a predeterminedtime schedule.
 29. The device defined by claim 28, said plurality ofretracting means each including a chain and having a predetermineddifferent length, a first end portion of each chain connected to theoutermost end of a different one of said plungers, a second end portionof each chain connected to said timing means, said chains being drawnaway from said plungers by said timing means.
 30. The device defined byclaim 29, the lengths of said chains determining the succession in whichthe plungers connected thereto are retracted, the plunger connected tothe shorter chain being retracted first and the plunger attached to thelongest chain being retracted last.
 31. The device defined by claim 29,said timing means including: a plurality of sprockets each positioned tobe engageable with a different one of said retracting means; and movermeans for driving said sprockets to have said retracting means engagedtherewith retract plungers connected thereto at said predeterminedtimes.
 32. The device defined by claim 29, said sprockets each having adiameter corresponding to a desired rate at which as associated plungeris to be retracted.
 33. The device defined by claim 32, wherein saidmover means is connected to rotate said sprockets in unison.
 34. Thedevice defined by claim 32, wherein said mover means is connected torotate said sprockets successively.
 35. The device defined by claim 33,said mover means including an armature that is adapted to be rotatedabout the longitudinal axis thereof, said armature being connected to atleast one of said sprockets to cause rotation thereof.
 36. An airsampling device for successively obtaining a plurality of air samples,said device comprising: a plurality of air sampler units each includinga cylindrical housing defining an interior cavity, an inlet needleconnected to said cavity, and a piston-like plunger housed in saidcavity for drawing an air sample through said inlet needle into saidcavity as said plunger is partially withdrawn from said cavity; aplurality of stopper means respectively connected with a different oneof said sampler units for covering the inlet needle thereof in responseto the plunger thereof being withdrawn from the cavity thEreof by apredetermined distance, said stopper means serving to prevent the escapeof an air sample through the inlet needle covered thereby; retractormeans connected to the plungers of said sampler units for partiallywithdrawing each plunger for said predetermined distance in accordancewith a selected time schedule.
 37. An air sampling device forautomatically obtaining an air sample, said device comprising: an airsampler unit including a housing defining an interior cavity, an inletneedle connected to said cavity, and a piston-like plunger housed insaid cavity for drawing an air sample through said inlet needle intosaid cavity as said plunger is partially withdrawn from said cavity;stopper means connected with said sampler unit for covering said inletneedle in response to the plunger thereof being withdrawn from saidcavity by a predetermined distance, said stopper means serving toprevent the escape of an air sample through said inlet needle coveredthereby; retractor means connected to said plunger for partiallywithdrawing said plunger for said predetermined distance.